KR20130133562A - Method of manufacturing window frame, and window frame manufactured thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a window frame in which a glass is installed inside and a window frame which is manufactured into one-piece according to the method. The above method comprises: a) a step of covering a frame shaped tube member with a braided fabric or a multi-axial warp knitted fabric in order to have a thickness corresponding to the shape of a longitudinal section of the window frame; b) a step of forming a window frame preform by making the tube member, which is covered by the braided fabric or the multi-axial warp knitted fabric, into a shape corresponding to the window frame; and c) a step of hardening by filling resin into the window frame preform. According to the manufacturing method of the present invention, the window frame can be easily formed into one-piece without a surface only made with resins by covering the frame shaped tube member with the braided fabric or the multi-axial warp knitted fabric in order to have a thickness corresponding to the shape of longitudinal section of the window frame and emitting gas for shrinkage and making the member into the shape corresponding to the window frame. The window frame manufactured by the above method not only is light weighted but has enhanced physical properties such as toughness, fatigue resistance, and impact resistance and the likes so that operating expanses of vehicles, flights and the likes can be reduced and users can elastically prepare for development trends of the vehicles, flights and the likes whose main bodies are formed with composite materials. [Reference numerals] (AA) Start;(BB) End;(S100) Step of covering a frame shaped tube member with a braided fabric or a multi-axial warp knitted fabric;(S200) Step of forming a window frame preform by making into a window frame form;(S300) Step of hardening by filling resin

Description

METHOD OF MANUFACTURING WINDOW FRAME, AND WINDOW FRAME MANUFACTURED THEREBY < RTI ID = 0.0 >

More particularly, the present invention relates to a method of manufacturing a window frame capable of forming an integral type preform by a simple method and a window frame manufactured by such a method and exhibiting excellent physical properties.

A window frame is a structure for mounting a window of a room such as a vehicle or an airplane, and is a circular, elliptical, or rectangular structure that is mounted on a main body in a line. A schematic structure of a rectangular window frame and its longitudinal section are shown in Figs. 1 and 2, respectively.

Conventionally, the window frame used in aircraft has been machined using aluminum. Recently, fuselage skin of aircraft has been changed to composite material in order to reduce operating cost through weight saving of aircraft. In addition, Window frames are also being replaced by composite materials.

Generally, window frames for aircraft are manufactured in two ways.

The first method is to cut the carbon fiber into staple fiber (chopped fiber) and mix it with an epoxy resin to form a sheet molding compound (SMC) As shown in FIG. 3, the method is a method of forming a window frame by stacking four types of prepregs together to form four pieces of preforms, and then molding them together.

The first method is simple and the productivity is good but the mechanical properties are weak. In the second method, most of the mechanical properties are relatively better than the first method. However, since the surface where the four preforms meet is composed of only the resin, Even when the co-curing is performed, the crack propagates rapidly due to compression or impact rather than the one-piece method, which shortens the fatigue life. In addition, since the production is complicated and the product is made by hand, it takes much time and has a disadvantage of poor reproducibility.

In order to solve the above-described problems, the present inventors have made a frame-shaped tube member and wound the structure on a braided fabric or a multi-axial warp knitted fabric, The present invention has been accomplished by confirming that a window frame improved in fatigue resistance, impact resistance and compressive resistance can be produced through an easy process of pressing the resin into a shape corresponding to a window frame and then filling and curing the resin.

Therefore, an object of the present invention is to provide a method of manufacturing a window frame which can be integrally formed without a surface made of only a resin in a simple manner, and a window frame which is manufactured by such a method and exhibits excellent physical properties.

According to the above object, the present invention provides a method of manufacturing a braided or multi-axial warp knitted fabric, comprising the steps of: a) forming a braid fabric or a multi-axial warp knitted fabric on a frame-shaped tube member to form a thickness corresponding to the shape of the longitudinal cross- step; b) forming a window frame preform by making the tube member wrapped with the strand or multi-axle knitted fabric into a shape corresponding to the window frame; And c) curing the window frame preform by filling the resin with resin.

According to another aspect of the present invention, there is provided a window frame made of a resin, which is made of a resin in accordance with the above method, and which is made of a one-piece.

The manufacturing method of the present invention is a method of wrapping a rectangular or multicyclone knitted fabric on a frame-shaped tube member so as to form a desired thickness (i.e., a thickness corresponding to the shape of a longitudinal section of a desired window frame) Since the window frame preform is made in the shape of a window frame, it is possible to easily manufacture an integral window frame without a surface made of resin alone.

In addition, the window frame manufactured in this way is not only light but also excellent in physical properties such as fatigue resistance, impact resistance and compressive resistance, so that it is possible to reduce the operation cost of vehicles, aircraft, and the like, It can flexibly prepare for development trends.

Figure 1 is a schematic perspective view of a generally rectangular window frame.
2 is a longitudinal sectional view taken along line II-II 'of FIG.
Fig. 3 is a longitudinal sectional view of a conventional window frame for an aircraft obtained by laminating four pieces of prepregs corresponding to Fig. 2; Fig.
4 is a flowchart schematically showing a method of manufacturing a window frame according to an embodiment of the present invention.
FIG. 5 is a schematic diagram of a tube member of a playground track shape according to an embodiment of the present invention. FIG.
FIG. 6 shows a schematic cross-sectional view of a window frame showing a process of deforming the longitudinal section of FIG. 2 into a circular shape.
Fig. 7 shows a cross-section of an n-fold structure or multiaxial warp yarns constituting the window frame of Fig. 6 in a laminated state.
8 is a schematic view showing a state in which a building is wrapped around a frame member in accordance with an embodiment of the present invention.
FIG. 9 shows a state in which stitching is performed to join the folds of the structures inside the frame member in accordance with an embodiment of the present invention.
10 is a schematic view showing a three-point bending test for specimens 1 to 8 and control specimens 1 to 4 according to ASTM D 790 method.
11 is a graph showing the bending strengths of specimens 1 to 8 and control specimens 1 to 4.
12 is a schematic view showing the tensile test of specimens 1 to 8 and control specimens 1 to 4 according to KS M 3381 method.
13 is a graph showing the tensile strengths of specimens 1 to 8 and control specimens 1 to 4.
Fig. 14 is a graph schematically showing a state in which a compression test is carried out for specimens 1 to 8 and control specimens 1 to 4 in accordance with KS M 3383 method.
15 is a graph showing the compressive strengths of specimens 1 to 8 and control specimens 1 to 4.

A method of manufacturing a window frame according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a flowchart schematically showing a method of manufacturing a window frame according to an embodiment of the present invention.

Referring to FIG. 4, first, a strand or multicyclone knitted fabric is wound on a frame-shaped tube member so as to have a desired thickness (S100).

In the present invention, the frame-shaped tube member is used as a template for fabricating a window frame in which a glass is to be mounted, and has a hollow part so as to be easily deformed into a shape corresponding to a window frame . Further, since the tube member is present in the window frame without being removed even after the deformation, it is preferable that the tube member is made of a light material in order to lighten a vehicle, an aircraft, and the like. The tube member may be made of a metal material such as aluminum, titanium, duralumin, or the like, or may be a film made of an epoxy resin or a similar resin (for example, Vinyl ester resin, unsaturated polyester resin, phenol resin, and the like).

The method of manufacturing the tubular member is not particularly limited as long as it is a method of manufacturing a frame-shaped member provided with a hollow portion. The size and shape of the tubular member are adjusted in consideration of the size and shape of the final window frame. For example, a frame-shaped tube member made of an epoxy resin film is obtained by cutting two epoxy resin films into a frame shape (for example, a track track shape, an ellipse shape, a circular shape, etc.) And then injecting a gas into the hollow portion formed by the two film bonds.

5 illustrates an elliptical tube member such as a playground track, but the present invention is not limited thereto.

On such a frame-shaped tube member, a woven fabric or multicomponent knitted fabric is wrapped as follows. Unlike the window frame preforms manufactured using short fibers, the window frame preforms prepared using the above-mentioned wood or polycrystalline knitted fabrics have a high packing factor due to the ordered arrangement of the fibers, As the fraction increases, the strength can be increased. In addition, when a window frame preform is produced using short fibers, physical properties are lowered by bucking or kinking of the fibers when a high pressure is applied to increase the volume fraction of the fibers. , The strength is not lowered even if the fiber volume fraction is increased to about 60%.

The step S100 includes weaving a braided fabric or a multi-axial warp knitted fabric so as to correspond to the shape of the longitudinal section of the window frame, and winding and laminating a knitted or multicolored knitted fabric on the tube member . ≪ / RTI >

As shown in FIG. 6, before the weaving step, the step of calculating the thickness of each part of the longitudinal section by making the longitudinal section circular, with respect to one point of the longitudinal section of the window frame. For example, as shown in FIG. 2, the thickness of each part of the longitudinal section can be calculated after making the longitudinal section circular, with respect to a point where lines bisecting each part of the longitudinal section of the window frame meet. The final thickness of the strand or multi-axis strand and the number of strands (number of strands) of the strand or multi-axis strand can be determined by this calculation process, and the above process can be performed by computer simulation or the like.

As shown in FIG. 7, depending on the thickness of the composite or multi-axle flexible sheet, the n-fold or multicyclone knitted fabric can be laminated on the tube member by winding a sheet or multi-shaft knitted fabric on the tube member.

The knitted and multicomponent knitted fabrics used in the present invention are a kind of cloth and can be woven according to methods known in the art. However, unlike a typical fabric, the fabric used in the present invention is woven by varying the thickness of the yarn or by changing the thickness of the axial yarn so that the thickness varies along the circumference perpendicular to the longitudinal direction of the tube member. That is, the present invention changes the thickness along the circumferential surface of the tubular member, which is perpendicular to the longitudinal direction of the tubular member, and overlaps the same thickness of the same thickness portion around the tubular member.

The multiaxial warp yarns used in the present invention are also woven by varying the thickness of yarns used at 0 degrees such that the thickness varies along the circumference perpendicular to the longitudinal direction of the tube member, The shrink knitted fabric varies in thickness along a circumferential surface perpendicular to the longitudinal direction of the tube member and overlaps with a multifactor knitted fabric portion of the same thickness at the same position around the circumferential surface when wrapped around the tube member.

In addition, in the present invention, the orientation of the braid yarns is changed in the fabrics according to the desired strength direction during weaving of the fabrics and the multifiber warp knitted fabrics, and the orientation angles can be changed in the multifactor knitted fabrics.

(Or multicomponent knitted fabric) is formed by laminating n pieces of knit (or multifunctional knit) knit already woven around the tube member in an open form, or with a dimension (width x width) corresponding to the length and circumference of the tube member It can also be wound in the form.

Unlike the woven fabric, the braided fabric and the multifunctional knitted fabric used in the present invention can be deformed without being wrinkled in a cylindrical shape due to easy shear deformation in straight and curved portions, (Or the thickness of yarn used at 0 °) of the center yarn may be varied. Both ends of the knitted fabric (or multicomponent knitted fabric) may be stitched on the inside of the tube member while being wrapped around the woven fabric (or multi-shaft knitted fabric), or may be joined using an adhesive or the like. The stitching of the fabric (or multifunctional knitted fabric) can be done manually or by a stitching apparatus, and the adhesive or the like can be applied by a method such as spraying. This process can prevent both ends of the article (or multi-shaft knitted fabric) from being loosened and maintain the proper material shape.

Fig. 8 schematically shows a structure wrapping around a tube member, and Fig. 9 shows a stitched state for joining the folds of the assemblies inside the tube member.

Next, the tubular member wrapped in the above-mentioned tubular or multiaxial knitted fabric is shaped into a shape corresponding to the window frame to form a window frame preform (S200).

The step S200 includes a step of breaking the tube member and a step of forming the broken tube member and the stranded or multicyclone knitted fabric wrapped by the tube member in a shape corresponding to the window frame by press molding or resin transfer molding RTM, Resin Transfer Molding).

For example, when the tube member is made of a resinous film, if the tube member is torn with a tool such as a needle, the gas filled in the tube member is discharged to the outside to shrink the tube member , The tube member thus contracted and the stranded or multicyclone knitted fabric wrapped around the tube member can be deformed into a desired window frame shape on the mold. On the other hand, when the tube member is made of a metal sheet, the tube member can be pressed and deformed into a shape of a desired window frame on the mold by pressing or the like. This process is similar to the method of using a liner when the mandrel can not be removed in the filament winding manufacturing method.

Finally, the formed window frame preform (i.e., a window frame shaped article and a tube member) is filled with resin and cured (S300).

The resin filling process can be selected from resin transfer molding (RTM), vacuum-assisted RTM (VaRTM), and autoclave processes well known in the art, and the RTM method is preferable. Resin may be VRM34 (Hexcel), RTM6 (Hexcel) or the like.

After resin filling, the resin filled window frame preform is cured using methods generally known in the art to obtain the desired window frame. For example, the filled resin can be cured at a temperature of about 70 to 90 < 0 > C.

The present invention also provides an excellent window frame which is integrally manufactured without a layer made of a resin alone and excellent in terms of compressibility, fatigue resistance, impact resistance and the like according to the above method.

The window frame according to the present invention is formed by wrapping a braid or multicyclone knitted fabric so as to form a thickness corresponding to the shape of the longitudinal section of the window frame on the frame-shaped tube member as described above, Since the resin is filled and cured after being made into a shape corresponding to the frame, it is possible to easily manufacture a window frame in an integrated form without a layer made only of a resin. Further, since the window frame of the present invention is manufactured using a composite material having excellent performance composed of a composite material (or a multifunctional knitted fabric) and a resin, it is not only light but also excellent in properties such as compression resistance, fatigue resistance, impact resistance, Vehicles, aircraft, etc., and it is possible to reduce the operation cost thereof, and to flexibly prepare for the development trend of the aircraft composed of the composite body in the future.

Although the present invention has been described in terms of a window frame for an aircraft, the present invention is merely illustrative and can be applied to a vehicle, a helicopter, a general building, and the like. Further, It is possible to carry out various modifications within the scope, and this is also within the scope of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

≪ Example 1 >

A frame member (epoxy resin film) was prepared (see Fig. 5). In addition, a three-axis (triaxial) blade machine was used to prepare the fabric (yarn: E-glass fiber (ER 600 from Korea Fiber Co., Ltd.), yarn thickness: 900 Denier). Thereafter, as shown in Fig. 9, both ends of the fabric were stitched continuously from the inside of the tube member while winding the fabric on the prepared tube member in an open form. Thereafter, the tube member surrounded by the blank was blown off with a needle, and then press-formed into a window frame shape using a mold to produce a window frame preform. Subsequently, a resin composition (epoxy resin / curing agent = 3/1, where YD-114 was used as an epoxy resin) was filled into the window frame by RTM (Resin Transfer Molding) molding method and cured at 80 ° C for 2 hours Window frame.

<Example 2>

Except that the multi-axially ground fabric (yarn: E-glass fiber (ER 600 from Korea Fiber Co., Ltd.), manufactured by Yasunami Kogyo Co., Ltd., 0 / 占 45 laminated layer) was used instead of the material used in Example 1, 1 to prepare a window frame.

&Lt; Experimental Example 1 > - Measurement of physical properties of window frames

1-1. Materials and specimen manufacturing

(a) material

- Yarn: E-Glass fiber (ER-600 from Korea Fiber Co., Ltd., thickness: 900 denier)

- Fabric: manufactured using triaxial braid machine

- Multifunctional knitted fabric: manufactured by YI San-san Co., 0 / ± 45 lamination

- Resin composition: Containing epoxy resin and curing agent (epoxy resin / curing agent = 3/1)

(b) Preparation of specimens 1 to 4

A prepared composite material was placed in a mold (40 mm x 200 mm), the resin composition was injected into the mold, and the mixture was cured at 80 ° C for 2 hours to prepare a composite material. At this time, specimens 1 to 4 were obtained by adjusting the glass fiber volume fraction of the composite material to 30, 40, 50 and 60%. Here, the glass fiber volume fraction was calculated by the following equation (1), and the thickness according to the fiber volume fraction of each sample was calculated according to the calculation result, and the sample according to each fiber volume fraction was manufactured. Table 1 below shows the calculation of the individual fiber volume fractions with the same thickness for the specimens 1 to 4.

(In the above formula (1)

V _f is the glass fiber volume (cm 3)

V _m is an epoxy resin volume (cm 3)

Fiber weight (g) No. of ply Fiber volume fraction (%) Psalm 1 7.7 3 30.1 Psalm 2 10.3 4 40.1 Psalm 3 12.9 5 50.2 Psalm 4 15.5 6 60.2

(c) Preparation of specimens 5 to 8

A multiaxial lightly knitted composite material was prepared in the same manner as the preparation of the matrix composite material, except that the multiaxial knitted fabric was used instead of the matrix used in the preparation of the matrix composite. At this time, specimens 5 to 8 were obtained by adjusting the glass fiber volume fraction of the multifunctional knitted composite material to 30, 40, 50 and 60%. In the preparation of each specimen, the volume fraction of each specimen was calculated from Equation (1) as in the above Specimens 1 to 4, and thicknesses thereof were calculated to prepare specimens corresponding to the respective fiber volume fractions. Table 2 below shows that the thicknesses of specimens 5 to 8 are the same, and the respective fiber volume fractions are calculated according to the weight.

Fiber weight (g) No. of ply Fiber volume fraction (%) Psalm 5 10.9 3 30.5 Psalm 6 14.5 4 40.6 Psalm 7 18.2 5 50.8 Psalm 8 21.8 6 61.0

(d) Preparation of control specimens 1 to 4

E-glass fiber (ER 600, thickness: 900 denier, manufactured by Korea Fiber Co., Ltd.) was cut into a length of 1 inch and then mixed with the prepared resin composition. The resultant was put into a mold (40 mm x 200 mm) Lt; / RTI &gt; to produce a short fiber composite material. At this time, control samples 1 to 4 were obtained by controlling the glass fiber volume fraction of the short fiber composite material to 30, 40, 50, and 60%. In the preparation of each specimen, the volume fraction of each specimen was calculated from Equation (1) as in the above Specimens 1 to 4, and thicknesses thereof were calculated to prepare specimens corresponding to the respective fiber volume fractions. Table 3 below shows the calculation of each fiber volume fraction according to the weight, with the thicknesses of the control specimens 1 to 4 being the same.

Fiber weight (g) Fiber volume fraction (%) Contrast Psalm 1 12.3 30.1 Control Psalm 2 16.4 40.1 Contrast Psalm 3 20.4 50.0 Contrast Psalm 4 30.6 60.0

1-2. Bending strength ( flexural strength ) Measure

1) A 3-point bending test was performed on specimens 1 to 8 and control specimens 1 to 4 according to ASTM D 790, and the bending strength was measured (see FIG. 10). The measurement results are shown in Fig. In the measurement, the cross-head speed was 2 mm / min, and the ratio of the support distance to the thickness of the specimen was 16: 1. Here, the bending strength was calculated by the following formula (2).

(In the above formula (1)

P is the maximum load (N)

L is the support distance (m)

b is the width (m) of the specimen,

t is the thickness of the specimen (m)

1-3. Tensile strength measurement

Tensile tests were carried out on specimens 1 to 8 and control specimens 1 to 4 according to KS M 3391 (see Fig. 12). The measurement results are shown in Fig. As shown in Fig. 12, a tab was attached to the end portion of the sample to prevent compression fracture of the specimen at the grip portion of the tensile tester. When measured, the cross-head speed was 1.5 mm / min.

1-4. Compressive strength measurement

Compression tests were carried out on specimens 1 to 8 and control specimens 1 to 4 according to KS M 3383 method (see FIG. 14). The measurement results are shown in Fig. During the measurement, the cross-head speed was 1.5 mm / min and the specimen length was 80 mm. The compressive strength was calculated by the following equation (3).

(In the above equation (2)

? is compressive strength (MPa),?

P is the compressive load (N) at failure,

A is the cross-sectional area of the specimen (mm 2)

1-5. result

1) As can be seen from FIG. 11, the specimens 1 to 4 had higher bending strengths with larger fiber volume fractions, which was also the case with specimens 5 to 8. That is, the bending strength of the composite fabric and the multifunctional knitted fabric composite increased as the fiber volume fraction increased. On the other hand, the control specimen 2 (fiber volume fraction: 40%) had higher bending strength than the control specimen 1 (fiber volume fraction: 30 5), but the control specimen 3 or 4 having a higher volume fraction of the fiber than the control specimen 2 And had bending strength similar to that of specimen 2. That is, in the case of the single-fiber composite material, the bending strength was not so high even if the volume fraction of the fibers increased.

2) As a result of tensile strength measurement, the tensile strength of specimens 1 to 8 was higher as the fiber volume fraction was larger, and the tensile strength was higher than that of control specimens 1 to 4 (see FIG. 12). In contrast, in the control specimens 1 to 4, the orientation of the short fibers was randomly arranged, so that the fibers arranged in the axial direction were relatively small and the tensile strength was considered to be lower due to the buckling effect of the fibers.

The tensile strength of the specimens 1 to 4 using the material was higher than that of the specimens 5 to 8 using the multimodal knitted fabric. It is thought that the orientation of the braid yarn is oriented not only not only in the axial direction but also in the case of the specimens 1 to 4, which is less than 45 ˚, so that many fibers are oriented in the axial direction.

3) As a result of the compressive strength measurement, the compression characteristics of the specimen 1 to 8 using the matrix composite material or the multifunctional knitted composite material were superior to the control specimens 1 to 4 using the single fiber composite material (see FIG. 15). In the case of specimens 1 to 8, the compressive strength was improved as the volume fraction of the fibers increased. On the other hand, the control specimens 1 to 4 had the maximum compressive strength at a fiber volume fraction of 40% %, The compressive strength was very low. In the case of the short fiber composite material, it is presumed that if the volume fraction of the fibers is increased, the resin is not properly penetrated (filled) between the fibers, and the micropores are present, thereby degrading the compression characteristics. The compression characteristics of the composite material are not only the characteristics of the fibers but also the number of defects in the composite material and the filling ratio of the matrix (resin composition). The fiber volume fraction of the monofilament composite material is 50% and 60% The more fibers are buckled, the more vacant spaces (micropores) are present between the fibers, so that even if a low compressive load is applied, cracks are generated from the empty space, .

4) Through the measurement results, when a window frame is manufactured using a window frame preform obtained by wrapping a frame-shaped tube member with a strand or multifocal knitted fabric and filling it with a resin and curing as in the present invention, It can be expected that properties such as bending strength, tensile strength and compressive strength can be remarkably improved at the same fiber volume fraction as compared with the conventional window frame using the material. In addition, when the window frame is manufactured according to the present invention, when the fiber volume fraction of the crucible or multi-axis fiber is adjusted to about 60%, the mass can be reduced to about 1/2 of that of the conventional window frame using the single fiber composite material Can be expected.

Claims (7)

a) wrapping a braided fabric or a multi-axial warp knitted fabric such that a thickness corresponding to the shape of the longitudinal section of the window frame is formed on the frame-shaped tube member;
b) forming a window frame preform by making the tubular member wrapped with the strand or multi-axis knitted fabric into a shape corresponding to a window frame; And
c) filling the window frame preform with resin and curing the resin;
The method comprising the steps of: The method of claim 1,
The step a)
a1) weaving the set or multicyclone knitted fabric so as to correspond to the shape of the longitudinal section of the window frame; And
a2) wrapping the woven or multicomponent knitted fabric on the tube member
&Lt; / RTI &gt; 3. The method of claim 2,
Further comprising the step of calculating the thickness of each part of the longitudinal section by making the longitudinal section circular with respect to one point of the longitudinal section of the window frame before step a1). 3. The method of claim 2,
Wherein both ends of the strand or multiaxial warp yarn are stiching on the inside of the tube member or are connected to each other at both ends using an adhesive in step a2). The method of claim 1,
Step b) is
b1) breaking the tube member; And
b2) press-molding the broken tube member and the composition or multi-axial warp knitted fabric wrapped in the tube member to a shape corresponding to the window frame using a mold;
&Lt; / RTI &gt; The method of claim 1,
The step c) is performed using one of the following processes selected from resin transfer molding (RTM), vacuum-assisted RTM, and autoclave process. A window frame manufactured in one piece according to the method of any one of claims 1 to 6.

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